1. Field of the Invention
The present invention relates to solar energy devices, and in particular relates to solar energy collectors adapted to combine the ability of curved reflectors to concentrate direct and indirect solar radiation and the ability of a flat plate collector to absorb and utilize direct and indirect solar radiation.
2. Description of the Prior Art
A wide variety of solar energy collecting devices are known in the prior art. Generally, solar collectors are of two types. The first type comprises collectors having curved surfaces which are adapted to concentrate the solar energy radiating directly on the reflective surface thereof. Such arrangements include parabolic and hemispherical dishes. In most of these curved dish arrangements, the substance to be heated is passed through the focal point of the curved, reflecting surface. Since indirect solar radiation is not reflected onto the focal point in such curved reflectors, it is common to employ means for moving the curved dish so as to track the sun during the solar day, in order to receive solar radiation directly onto the reflective surface. An arrangement of this type is disclosed in U.S. Pat. No. 1,424,932 to Moreau.
A second type of solar collector is generally referred to as a flat plate collector, because the collecting element is disposed along a flat surface. Such flat plate collectors are capable of absorbing both direct and indirect solar radiation, but are not capable of reaching the high temperatures which characterize the operation of the curved dish collectors. Examples of flat plate collectors are found in the following U.S. Pat. Nos. 3,599,626 to Bouse et al; 3,464,402 to Collura; 3,390,672 to Snelling; 3,299,881 to Kotch; 3,039,453 to Andrassy; 3,022,781 to Andrassy; 2,838,043 to Bliss; and 2,316,191 to Scott.
In U.S. Pat. No. 3,321,012, Hervey discloses a trough reflector having a semi-circular cross section, with a flat plate collector disposed on the apex line thereof. As disclosed by Hervey, this arrangement is capable of absorbing both direct and indirect solar radiation, since indirect radiation is reflected off of the reflective surface and against the flat plate collector. The flat plate collector disclosed by Hervey comprises a single, flat tube extending along the apex line through the trough, and through which water flows in order to absorb the heat energy generated by solar radiation.
Other prior art references of interest include the following U.S. Pat. Nos. 2,770,229 to Tarcici; 3,023,257 to Fritts; 3,038,463 to Daymon; 2,859,745 to Brudersdorff; 2,690,463 to Clevett et al; 3,130,074 to Loring; 2,994,318 to Lee; 3,295,512 to McCusker; and 3,310,102 to Trombe. Additional prior art references may be found in Patent Office class 126, subclass 270; class 60, subclass 641; class 136, subclass 206; and class 165, subclass 40, among others.